I am having trouble with my app. The problem I am having is that when I leave a text field empty I want it to have a pop-up message that says empty text field and I want it to stop the segue from moving to the next screen. What is happening is it is showing the pop-up message of the empty text field but it still moves to the next screen. This is the code that I currently have:
let firstNameAlert : UIAlertView = UIAlertView(title: "Blank Text Field", message: "Please fill in first name.", delegate: nil, cancelButtonTitle: "OK")
let lastNameAlert : UIAlertView = UIAlertView(title: "Blank Text Field", message: "Please fill in last name.", delegate: nil, cancelButtonTitle: "OK")
let emailAlert : UIAlertView = UIAlertView(title: "Blank Text Field", message: "Please fill in email.", delegate: nil, cancelButtonTitle: "OK")
let addressAlert : UIAlertView = UIAlertView(title: "Blank Text Field", message: "Please fill in address.", delegate: nil, cancelButtonTitle: "OK")
let phoneFromDefaults = defaults.object(forKey: "Phone Number") as? String
if firstName.text == ""{
firstNameAlert.show()
}else if lastName.text == ""{
lastNameAlert.show()
}else if email.text == ""{
emailAlert.show()
}else if addressLine1.text == ""{
addressAlert.show()
}else{
performSegue(withIdentifier: "Create Account", sender: AnyObject.self)
}